This invention relates to an electrostatic shielding sheet for making a box used for shipping and storing electronic components and/or assemblies. The invention comprises a shipping box made thereof, too.
Specialty industries as aerospace, electronics, chemistry, medicine and the like are in need of electrostatic shielding packaging materials as well as a packaging for the shipping and the storing of ESD sensitive products which may be harmed by Electrostatic Discharge (ESD) during storage and shipping. ESD has become an increasing threat to electronic components, subassemblies and assemblies. With the decreasing geometry of VLSI circuits (Very Large Scale Integration), Mos technology and circuit speed performance, today's electronic components may be harmed by ESD of less than 2000 Volts. Electrostatic discharges may cause a total failure of the device and even worse they may lead to latent failures which reduce the reliability and the functionality of the circuits. It is a major goal for the industries cited above to prevent damage caused by ESD by using a protective packaging. Built-in circuitry for ESD protection is limited by chip size and speed.
For these objects, a normal cardboard is on the market which is coated on one side--or both sides--with a black, carbon loaded and conductive, thin layer which--applied to the cardboard--provides an electrostatic shielding. This black conductive coated cardboard does not meet all the requirements needed from a safe electrostatic shielding packaging; it may cause contamination of the circuits by conductive Carbon black particles which may be deposited on the circuits during the handling of the circuits and the boxes as well as malfunctions. Because of the nature and the thickness of the Carbon black conductive coating, the shielding effectiveness is not high enough to eliminate or to attenuate the ESD level found in non ESD protected areas as shipping; finally, the black conductive coated cardboard cannot be recycled with normal cardboard and must be processed seperately as it needs special treatment to get rid of the Carbon black coating.
Knowing this prior art, it has been an object of the inventor to provide a material sheet of the above mentioned kind avoiding the known failings of which shipping boxes and containers in a wide variety of sizes and shapes can be made with electrostatic dissipative and electrostatic shielding properties to protect electronic products according to the recommendations of the European ESD standard CECC-00015/1. Additionally, an environmentally responsible material shall be created which can be recycled with normal cardboard.